diff --git a/.gitattributes b/.gitattributes
index 097986bb..bf70f378 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -14,6 +14,9 @@
 /src/stub/src/arch/**/lzma_d_c[fns].S   linguist-generated
 /src/stub/tmp/**                        linguist-generated
 
+/misc/podman/*/packages*.txt            linguist-generated
+/misc/testsuite/*expected_sha256sums*   linguist-generated
+
 #
 # make GitHub language detection more accurate
 #
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 52a7641e..4be09ffe 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -92,13 +92,13 @@ jobs:
         if: ${{ matrix.use_m32 }}
         run:   'make build/extra/gcc-m32/debug'
       - name: 'Build cmake extra/gcc-m32/release'
-        if: ${{ matrix.use_m32 }}
+        if: ${{ matrix.use_m32 && (success() || failure()) }} # run this step even if the previous step failed
         run:   'make build/extra/gcc-m32/release'
       - name: 'Build cmake extra/cross-windows-mingw32/release'
-        if: ${{ matrix.use_m32 }}
+        if: ${{ matrix.use_m32 && (success() || failure()) }} # run this step even if the previous step failed
         run:   'make build/extra/cross-windows-mingw32/release'
       - name: 'Build cmake extra/cross-windows-mingw64/release'
-        if: ${{ matrix.use_m32 }}
+        if: ${{ matrix.use_m32 && (success() || failure()) }} # run this step even if the previous step failed
         run:   'make build/extra/cross-windows-mingw64/release'
       - name: 'Make artifact'
         run: |
@@ -206,7 +206,8 @@ jobs:
         if: ${{ !contains(matrix.os, 'macos-13') }} # FIXME: UPX on macos-13 is broken => disable self-test for now
         run: |
           make -C build/extra/clang/debug test
-#         make -C build/extra/clang/release test
+          #make -C build/extra/clang/release test
+          for f in ./build/extra/*/*/upx; do echo "===== $f"; $f --sysinfo -v; done
       - name: 'Run file system test suite'
         if: ${{ matrix.testsuite }} # for coreutils readlink
         run: |
@@ -235,6 +236,7 @@ jobs:
           - { name: windows-2019-amd64, os: windows-2019, vsversion: 2019, arch: amd64 }
           - { name: windows-2022-amd64, os: windows-2022, vsversion: 2022, arch: amd64 }
     steps:
+      - run: git config --global core.autocrlf false
       - name: 'Check out code'
         uses: actions/checkout@v4
         with: { submodules: true }
@@ -283,7 +285,6 @@ jobs:
     env:
       C: ${{ matrix.name }}
       B: release
-      H: 'd:\a\upx\upx'
     strategy:
       fail-fast: false
       matrix:
@@ -297,6 +298,7 @@ jobs:
           - { name: i386-win32-vs2019,    os: windows-2019, vsversion: 2019, arch: amd64_x86 }
           - { name: i386-win32-vs2022,    os: windows-2022, vsversion: 2022, arch: amd64_x86 }
     steps:
+      - run: git config --global core.autocrlf false
       - name: 'Check out code'
         uses: actions/checkout@v4
         with: { submodules: true }
@@ -305,6 +307,8 @@ jobs:
         run: |
           git clone --depth=1 https://github.com/upx/upx-testsuite ../deps/upx-testsuite
           mkdir -p -v build/$C/$B/{bzip2,ucl,upx,zlib,zstd}
+          repo_name="${GITHUB_REPOSITORY##*/}" # basename
+          echo "H=d:\\a\\$repo_name\\$repo_name" >> $GITHUB_ENV
       - name: 'Set up Developer Command Prompt'
         uses: ilammy/msvc-dev-cmd@cec98b9d092141f74527d0afa6feb2af698cfe89 # v1.12.1
         with:
@@ -370,6 +374,7 @@ jobs:
           cd $Env:H\build\$Env:C\$Env:B\upx
           $Env:UPX = "--no-color --no-progress"
           .\upx.exe --version
+          .\upx.exe --sysinfo -v
           .\upx.exe upx.exe -o upx_packed.exe
           dir *.exe
           .\upx.exe -l upx_packed.exe
diff --git a/.github/workflows/test-alpine-linux.yml b/.github/workflows/test-alpine-linux.yml
index f88a5692..7a19f0f5 100644
--- a/.github/workflows/test-alpine-linux.yml
+++ b/.github/workflows/test-alpine-linux.yml
@@ -21,7 +21,7 @@ jobs:
       - name: ${{ format('Build clang {0}', matrix.container) }}
         run: |
           apk update && apk upgrade && apk add clang cmake make
-          wget https://github.com/upx/upx/releases/download/v4.2.0/upx-4.2.0-src.tar.xz
+          wget https://github.com/upx/upx/releases/download/v4.2.1/upx-4.2.1-src.tar.xz
           tar -xoaf upx-*-src.tar.xz
           cd upx-*-src
           make    build/debug   CC="clang -static" CXX="clang++ -static"
@@ -48,7 +48,7 @@ jobs:
       - name: ${{ format('Build gcc {0}', matrix.container) }}
         run: |
           apk update && apk upgrade && apk add cmake g++ make
-          wget https://github.com/upx/upx/releases/download/v4.2.0/upx-4.2.0-src.tar.xz
+          wget https://github.com/upx/upx/releases/download/v4.2.1/upx-4.2.1-src.tar.xz
           tar -xoaf upx-*-src.tar.xz
           cd upx-*-src
           make    build/debug   CC="gcc -static" CXX="g++ -static"
diff --git a/.github/workflows/test-cmake-default.yml b/.github/workflows/test-cmake-default.yml
index 64fada6a..9bac0a3c 100644
--- a/.github/workflows/test-cmake-default.yml
+++ b/.github/workflows/test-cmake-default.yml
@@ -51,6 +51,7 @@ jobs:
   cmake-nmake:
     runs-on: windows-2022
     steps:
+      - run: git config --global core.autocrlf false
       - name: 'Check out code'
         uses: actions/checkout@v4
         with: { submodules: true }
@@ -100,6 +101,7 @@ jobs:
   cmake-vsstudio-multi-config:
     runs-on: windows-2022
     steps:
+      - run: git config --global core.autocrlf false
       - name: 'Check out code'
         uses: actions/checkout@v4
         with: { submodules: true }
diff --git a/.github/workflows/weekly-ci-bs-by-hand.yml b/.github/workflows/weekly-ci-bs-by-hand.yml
index 7921b869..854fd368 100644
--- a/.github/workflows/weekly-ci-bs-by-hand.yml
+++ b/.github/workflows/weekly-ci-bs-by-hand.yml
@@ -141,7 +141,7 @@ jobs:
           cd "upx with space"/build/by-hand
           bash "$testsuite"
 
-  job-by-hand-windows-gcc: # uses a POSIX-compliant shell
+  job-by-hand-windows: # uses a POSIX-compliant shell
     # ...and also uses a subdirectory "upx with space" in order to detect possible quoting issues
     if: github.repository_owner == 'upx'
     strategy:
@@ -150,16 +150,29 @@ jobs:
         include:
           - { os: windows-2019 }
           - { os: windows-2022 }
-    name: ${{ format('by-hand gcc {0}', matrix.os) }}
+    name: ${{ format('by-hand cc {0}', matrix.os) }}
     runs-on: ${{ matrix.os }}
     steps:
+      - run: git config --global core.autocrlf false
       - name: ${{ format('Check out UPX {0} source code', github.ref_name) }}
         shell: bash
         run: |
           git clone --branch "$GITHUB_REF_NAME" --depth 1 "$GITHUB_SERVER_URL/$GITHUB_REPOSITORY" "upx with space"
           git -C "upx with space" submodule update --init
-      - name: 'Build by-hand with bash'
+      - name: 'Build by-hand with bash - clang'
         shell: bash
         run: |
           xflags="-static -Wall -Wextra -Werror"
+          # clang uses the MSVC headers, adjust settings
+          xflags="$xflags -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS"
+          export zlib_extra_flags="-DHAVE_VSNPRINTF"
+          export AR=false # link without using $AR
+          CC="clang $xflags" CXX="clang++ -std=gnu++17 $xflags" bash "./upx with space/misc/scripts/build_upx_by_hand.sh"
+          ls -l build/by-hand || true
+      - name: 'Build by-hand with bash - gcc'
+        if: success() || failure() # run this step even if the previous step failed
+        shell: bash
+        run: |
+          xflags="-static -Wall -Wextra -Werror"
+          # gcc uses the MingGW headers, so no extra settings are needed
           CC="gcc $xflags" CXX="g++ -std=gnu++17 $xflags" bash "./upx with space/misc/scripts/build_upx_by_hand.sh"
diff --git a/.github/workflows/weekly-ci-bs-cmake-macos-xcode.yml b/.github/workflows/weekly-ci-bs-cmake-macos-xcode.yml
index e2f68c4f..53e9d1ed 100644
--- a/.github/workflows/weekly-ci-bs-cmake-macos-xcode.yml
+++ b/.github/workflows/weekly-ci-bs-cmake-macos-xcode.yml
@@ -47,7 +47,9 @@ jobs:
         if: ${{ matrix.run_test }}
         run: |
           ctest --test-dir build/xcode -C Debug
-#         ctest --test-dir build/xcode -C Release
+          #ctest --test-dir build/xcode -C Release
+          ./build/xcode/Debug/upx --sysinfo -v
+          ./build/xcode/Release/upx --sysinfo -v
       - name: 'Run install tests'
         run: |
           (cd build/xcode && DESTDIR=$PWD/Install-default cmake --install .)
diff --git a/.github/workflows/weekly-ci-bs-cmake-windows-make.yml b/.github/workflows/weekly-ci-bs-cmake-windows-make.yml
index 0cd31e1a..a58a8247 100644
--- a/.github/workflows/weekly-ci-bs-cmake-windows-make.yml
+++ b/.github/workflows/weekly-ci-bs-cmake-windows-make.yml
@@ -43,6 +43,7 @@ jobs:
     name: ${{ format('{0} {1} {2}', matrix.cc, matrix.vsversion, matrix.arch) }}
     runs-on: ${{ matrix.os }}
     steps:
+      - run: git config --global core.autocrlf false
       - name: 'Check out code'
         uses: actions/checkout@v4
         with: { submodules: true }
@@ -64,6 +65,7 @@ jobs:
           ls -l build/xtarget/$xtarget/debug/upx.exe
           file  build/xtarget/$xtarget/debug/upx.exe || true
       - name: 'Build cmake Make Release'
+        if: success() || failure() # run this step even if the previous step failed
         shell: bash
         run: |
           make UPX_XTARGET=$xtarget xtarget/release
@@ -88,6 +90,8 @@ jobs:
         run: |
           ctest --test-dir build/xtarget/$xtarget/debug
           ctest --test-dir build/xtarget/$xtarget/release
+          ./build/xtarget/$xtarget/debug/upx.exe --sysinfo -v
+          ./build/xtarget/$xtarget/release/upx.exe --sysinfo -v
       - name: 'Run install tests'
         shell: bash
         run: |
diff --git a/.github/workflows/weekly-ci-bs-cmake-windows-ninja.yml b/.github/workflows/weekly-ci-bs-cmake-windows-ninja.yml
index a04260a7..b58bb87a 100644
--- a/.github/workflows/weekly-ci-bs-cmake-windows-ninja.yml
+++ b/.github/workflows/weekly-ci-bs-cmake-windows-ninja.yml
@@ -41,6 +41,7 @@ jobs:
     name: ${{ format('{0} {1} {2}', matrix.cc, matrix.vsversion, matrix.arch) }}
     runs-on: ${{ matrix.os }}
     steps:
+      - run: git config --global core.autocrlf false
       - name: 'Check out code'
         uses: actions/checkout@v4
         with: { submodules: true }
@@ -63,6 +64,7 @@ jobs:
           ls -l build/xtarget/$xtarget/debug/upx.exe
           file  build/xtarget/$xtarget/debug/upx.exe || true
       - name: 'Build cmake Ninja Release'
+        if: success() || failure() # run this step even if the previous step failed
         shell: bash
         run: |
           make UPX_XTARGET=$xtarget xtarget/release
@@ -87,6 +89,8 @@ jobs:
         run: |
           ctest --test-dir build/xtarget/$xtarget/debug
           ctest --test-dir build/xtarget/$xtarget/release
+          ./build/xtarget/$xtarget/debug/upx.exe --sysinfo -v
+          ./build/xtarget/$xtarget/release/upx.exe --sysinfo -v
       - name: 'Run install tests'
         shell: bash
         run: |
diff --git a/.github/workflows/weekly-ci-bs-cmake-windows-nmake.yml b/.github/workflows/weekly-ci-bs-cmake-windows-nmake.yml
index 10a8b701..3acf60c0 100644
--- a/.github/workflows/weekly-ci-bs-cmake-windows-nmake.yml
+++ b/.github/workflows/weekly-ci-bs-cmake-windows-nmake.yml
@@ -18,6 +18,7 @@ jobs:
       matrix:
         include:
           # clang-cl
+          - { os: windows-2019, vsversion: 2019, arch: amd64, clang_cl: true }
           - { os: windows-2022, vsversion: 2022, arch: amd64, clang_cl: true }
           # msvc
           - { os: windows-2019, vsversion: 2019, arch: amd64 }
@@ -29,6 +30,7 @@ jobs:
     name: ${{ format('vs{0} {1} {2}', matrix.vsversion, matrix.arch, matrix.clang_cl && 'clang-cl' || '') }}
     runs-on: ${{ matrix.os }}
     steps:
+      - run: git config --global core.autocrlf false
       - name: 'Check out code'
         uses: actions/checkout@v4
         with: { submodules: true }
@@ -46,6 +48,7 @@ jobs:
           nmake
           dir *.exe
       - name: 'Build cmake NMake Release'
+        if: success() || failure() # run this step even if the previous step failed
         shell: cmd
         run: |
           set X=${{ matrix.clang_cl && '-DCMAKE_C_COMPILER=clang-cl -DCMAKE_CXX_COMPILER=clang-cl' || '' }}
@@ -72,6 +75,8 @@ jobs:
         run: |
           ctest --test-dir build/debug
           ctest --test-dir build/release
+          .\build\debug\upx.exe --sysinfo -v
+          .\build\release\upx.exe --sysinfo -v
       - name: 'Run install tests'
         run: |
           env DESTDIR=./Install-debug   cmake --install build/debug
diff --git a/.github/workflows/weekly-ci-cc-alpine-mingw.yml b/.github/workflows/weekly-ci-cc-alpine-mingw.yml
index 81f27676..60267574 100644
--- a/.github/workflows/weekly-ci-cc-alpine-mingw.yml
+++ b/.github/workflows/weekly-ci-cc-alpine-mingw.yml
@@ -112,6 +112,7 @@ jobs:
           wine=wine64
           tt='./upx.exe'
           $wine ./upx.exe --version-short
+          $wine ./upx.exe --sysinfo -v
           $wine ./upx.exe -3 $tt -o tt.packed.exe
           $wine ./upx.exe -l tt.packed.exe
           $wine ./upx.exe -t tt.packed.exe
@@ -130,6 +131,7 @@ jobs:
           wine=wine64
           tt='./upx.exe'
           $wine ./upx.exe --version-short
+          $wine ./upx.exe --sysinfo -v
           $wine ./upx.exe -3 $tt -o tt.packed.exe
           $wine ./upx.exe -l tt.packed.exe
           $wine ./upx.exe -t tt.packed.exe
@@ -148,6 +150,7 @@ jobs:
           wine=wine64
           tt='./upx.exe'
           $wine ./upx.exe --version-short
+          $wine ./upx.exe --sysinfo -v
           $wine ./upx.exe -3 $tt -o tt.packed.exe
           $wine ./upx.exe -l tt.packed.exe
           $wine ./upx.exe -t tt.packed.exe
@@ -166,6 +169,7 @@ jobs:
           wine=wine64
           tt='./upx.exe'
           $wine ./upx.exe --version-short
+          $wine ./upx.exe --sysinfo -v
           $wine ./upx.exe -3 $tt -o tt.packed.exe
           $wine ./upx.exe -l tt.packed.exe
           $wine ./upx.exe -t tt.packed.exe
diff --git a/.github/workflows/weekly-ci-cc-llvm-mingw.yml b/.github/workflows/weekly-ci-cc-llvm-mingw.yml
index 3c86a78e..b7be9393 100644
--- a/.github/workflows/weekly-ci-cc-llvm-mingw.yml
+++ b/.github/workflows/weekly-ci-cc-llvm-mingw.yml
@@ -26,12 +26,12 @@ jobs:
           - name: llvm-mingw-20230614-ucrt
             llvm_version: 16.0.6
             url: 'https://github.com/mstorsjo/llvm-mingw/releases/download/20230614/llvm-mingw-20230614-ucrt-ubuntu-20.04-x86_64.tar.xz'
-          - name: llvm-mingw-20231017-msvcrt
-            llvm_version: 17.0.3
-            url: 'https://github.com/mstorsjo/llvm-mingw/releases/download/20231017/llvm-mingw-20231017-msvcrt-ubuntu-20.04-x86_64.tar.xz'
-          - name: llvm-mingw-20231017-ucrt
-            llvm_version: 17.0.3
-            url: 'https://github.com/mstorsjo/llvm-mingw/releases/download/20231017/llvm-mingw-20231017-ucrt-ubuntu-20.04-x86_64.tar.xz'
+          - name: llvm-mingw-20231031-msvcrt
+            llvm_version: 17.0.4
+            url: 'https://github.com/mstorsjo/llvm-mingw/releases/download/20231031/llvm-mingw-20231031-msvcrt-ubuntu-20.04-x86_64.tar.xz'
+          - name: llvm-mingw-20231031-ucrt
+            llvm_version: 17.0.4
+            url: 'https://github.com/mstorsjo/llvm-mingw/releases/download/20231031/llvm-mingw-20231031-ucrt-ubuntu-20.04-x86_64.tar.xz'
     name: ${{ format('{0} {1}', matrix.name, matrix.llvm_version) }}
     runs-on: ubuntu-latest
     steps:
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 64c199da..001980cf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -429,7 +429,7 @@ upx_sanitize_target(${t})
 if(MSVC_FRONTEND)
     target_compile_options(${t} PRIVATE ${warn_WN} -wd4127 -wd4244 -wd4267 ${warn_WX})
 else()
-    target_compile_options(${t} PRIVATE ${warn_Wall} -Wno-implicit-fallthrough ${warn_Werror})
+    target_compile_options(${t} PRIVATE ${warn_Wall} ${warn_Werror})
 endif()
 endif() # UPX_CONFIG_DISABLE_BZIP2
 
@@ -453,8 +453,8 @@ endif()
 if(MSVC_FRONTEND)
     target_compile_options(${t} PRIVATE -W3 ${warn_WX})
 else()
-    target_compile_options(${t} PRIVATE -Wall ${warn_Werror})
-    ##target_compile_options(${t} PRIVATE ${warn_Wall} -Wno-cast-align -Wno-cast-qual ${warn_Werror})
+    ##target_compile_options(${t} PRIVATE -Wall ${warn_Werror})
+    target_compile_options(${t} PRIVATE ${warn_Wall} -Wno-cast-align -Wno-cast-qual ${warn_Werror})
 endif()
 
 if(NOT UPX_CONFIG_DISABLE_ZSTD)
@@ -524,6 +524,7 @@ include(CTest)
 if(NOT CMAKE_CROSSCOMPILING)
     add_test(NAME upx-version COMMAND upx --version)
     add_test(NAME upx-help    COMMAND upx --help)
+    add_test(NAME upx-sysinfo COMMAND upx --sysinfo)
 endif()
 if(NOT CMAKE_CROSSCOMPILING AND NOT UPX_CONFIG_DISABLE_SELF_PACK_TEST)
     # IMPORTANT NOTE: these tests can only work if the host executable format is supported by UPX!
diff --git a/misc/scripts/build_upx_by_hand.sh b/misc/scripts/build_upx_by_hand.sh
index fc3d2aed..af4cb309 100755
--- a/misc/scripts/build_upx_by_hand.sh
+++ b/misc/scripts/build_upx_by_hand.sh
@@ -27,13 +27,13 @@ fi
 # protect against security threats caused by misguided compiler "optimizations"
 mandatory_flags="-fno-strict-aliasing -fno-strict-overflow -funsigned-char"
 # not mandatory but good practice when using <windows.h>:
-mandatory_flags="$mandatory_flags -DWIN32_LEAN_AND_MEAN"
+sensible_flags="-DWIN32_LEAN_AND_MEAN"
 if test "x$OPTIMIZE" != "x" && test "x$OPTIMIZE" != "x0"; then
     # not mandatory and not minimal, but usually a good idea:
-    mandatory_flags="-Wall -O2 $mandatory_flags"
+    sensible_flags="-Wall -O2 $sensible_flags"
 fi
-CC="$CC $mandatory_flags"
-CXX="$CXX $mandatory_flags"
+CC="$CC $sensible_flags $mandatory_flags"
+CXX="$CXX $sensible_flags $mandatory_flags"
 
 # go to upx top-level directory
 # HINT: set "top_srcdir" manually if your system does not have "readlink"
@@ -93,8 +93,9 @@ check_submodule() {
 # build
 run "+" mkdir -p "build/by-hand"
 if check_submodule bzip2; then
+    test -z "${bzip2_extra_flags+set}" && bzip2_extra_flags=
     for f in "$rel_top_srcdir"/vendor/bzip2/*.c; do
-        run "CC  $f" $CC -c "$f"
+        run "CC  $f" $CC $bzip2_extra_flags -c "$f"
     done
 fi
 if check_submodule ucl; then
@@ -103,13 +104,15 @@ if check_submodule ucl; then
     done
 fi
 if check_submodule zlib; then
+    test -z "${zlib_extra_flags+set}" && zlib_extra_flags="-DHAVE_UNISTD_H -DHAVE_VSNPRINTF"
     for f in "$rel_top_srcdir"/vendor/zlib/*.c; do
-        run "CC  $f" $CC -DHAVE_UNISTD_H -DHAVE_VSNPRINTF -c "$f"
+        run "CC  $f" $CC $zlib_extra_flags -c "$f"
     done
 fi
 if check_submodule zstd; then
+    test -z "${zstd_extra_flags+set}" && zstd_extra_flags="-DDYNAMIC_BMI2=0 -DZSTD_DISABLE_ASM"
     for f in "$rel_top_srcdir"/vendor/zstd/lib/*/*.c; do
-        run "CC  $f" $CC -DDYNAMIC_BMI2=0 -DZSTD_DISABLE_ASM -c "$f"
+        run "CC  $f" $CC $zstd_extra_flags -c "$f"
     done
 fi
 run "+" cd "$rel_top_srcdir" || exit 1
diff --git a/src/compress/compress_zstd.cpp b/src/compress/compress_zstd.cpp
index c08c17e9..2f585e4d 100644
--- a/src/compress/compress_zstd.cpp
+++ b/src/compress/compress_zstd.cpp
@@ -221,6 +221,7 @@ TEST_CASE("upx_zstd_decompress") {
     d_len = 31;
     r = upx_zstd_decompress(c_data, 16, d_buf, &d_len, M_ZSTD, nullptr);
     CHECK(r == UPX_E_OUTPUT_OVERRUN);
+    UNUSED(r);
 }
 
 #endif // WITH_ZSTD
diff --git a/src/headers.h b/src/headers.h
index 5b2ddc83..1f2a8fc9 100644
--- a/src/headers.h
+++ b/src/headers.h
@@ -152,4 +152,10 @@ static_assert(sizeof(void *) == 8);
 #endif
 #endif
 
+#ifdef WANT_WINDOWS_LEAN_H
+#if defined(_WIN32) || defined(__CYGWIN__)
+#include "util/windows_lean.h"
+#endif
+#endif
+
 /* vim:set ts=4 sw=4 et: */
diff --git a/src/help.cpp b/src/help.cpp
index 1d98f90e..981bb1ac 100644
--- a/src/help.cpp
+++ b/src/help.cpp
@@ -25,6 +25,7 @@
    <markus@oberhumer.com>               <ezerotven+github@gmail.com>
  */
 
+#define WANT_WINDOWS_LEAN_H 1 // _WIN32_WINNT
 #include "conf.h"
 #include "compress/compress.h" // upx_ucl_version_string()
 // for list_all_packers():
@@ -449,19 +450,51 @@ void show_sysinfo(const char *options_var) {
         con_fprintf(f, "UPX version: ");
         fflush(f);
         show_version(true);
+        con_fprintf(f, "UPX version internal: 0x%06x %s\n", UPX_VERSION_HEX, UPX_VERSION_STRING);
     }
     fflush(stdout);
 
     // Compilation Flags
-    if (opt->verbose >= 2) {
+    {
         size_t cf_count = 0;
-        auto cf_print = [f, &cf_count](const char *name, const char *fmt, upx_int64_t v) noexcept {
+        auto cf_print = [f, &cf_count](const char *name, const char *fmt, upx_int64_t v,
+                                       int need_verbose = 2) noexcept {
+            if (opt->verbose < need_verbose)
+                return;
             if (cf_count++ == 0)
                 con_fprintf(f, "\nCompilation flags:\n");
             con_fprintf(f, "  %s = ", name);
             con_fprintf(f, fmt, v);
             con_fprintf(f, "\n");
         };
+        // compiler
+#if defined(ACC_CC_CLANG)
+        cf_print("ACC_CC_CLANG", "0x%06llx", ACC_CC_CLANG + 0, 3);
+#endif
+#if defined(ACC_CC_GNUC)
+        cf_print("ACC_CC_GNUC", "0x%06llx", ACC_CC_GNUC + 0, 3);
+#endif
+#if defined(ACC_CC_MSC)
+        cf_print("ACC_CC_MSC", "%lld", ACC_CC_MSC + 0, 3);
+#endif
+#if defined(__clang__)
+        cf_print("__clang__", "%lld", __clang__ + 0);
+#endif
+#if defined(__clang_major__)
+        cf_print("__clang_major__", "%lld", __clang_major__ + 0);
+#endif
+#if defined(__GNUC__)
+        cf_print("__GNUC__", "%lld", __GNUC__ + 0);
+#endif
+#if defined(__GNUC_MINOR__)
+        cf_print("__GNUC_MINOR__", "%lld", __GNUC_MINOR__ + 0);
+#endif
+#if defined(_MSC_VER)
+        cf_print("_MSC_VER", "%lld", _MSC_VER + 0);
+#endif
+#if defined(_MSC_FULL_VER)
+        cf_print("_MSC_FULL_VER", "%lld", _MSC_FULL_VER + 0);
+#endif
         // OS and libc
 #if defined(WINVER)
         cf_print("WINVER", "0x%04llx", WINVER + 0);
@@ -473,21 +506,16 @@ void show_sysinfo(const char *options_var) {
         cf_print("__MSVCRT_VERSION__", "0x%04llx", __MSVCRT_VERSION__ + 0);
 #endif
 #if defined(_USE_MINGW_ANSI_STDIO)
-        cf_print("_USE_MINGW_ANSI_STDIO", "%lld", _USE_MINGW_ANSI_STDIO + 0);
+        cf_print("_USE_MINGW_ANSI_STDIO", "%lld", _USE_MINGW_ANSI_STDIO + 0, 3);
 #endif
 #if defined(__USE_MINGW_ANSI_STDIO)
-        cf_print("__USE_MINGW_ANSI_STDIO", "%lld", __USE_MINGW_ANSI_STDIO + 0);
+        cf_print("__USE_MINGW_ANSI_STDIO", "%lld", __USE_MINGW_ANSI_STDIO + 0, 3);
 #endif
 #if defined(__GLIBC__)
         cf_print("__GLIBC__", "%lld", __GLIBC__ + 0);
 #endif
 #if defined(__GLIBC_MINOR__)
         cf_print("__GLIBC_MINOR__", "%lld", __GLIBC_MINOR__ + 0);
-#endif
-        // compiler
-#if defined(_MSC_VER) && defined(_MSC_FULL_VER)
-        cf_print("_MSC_VER", "%lld", _MSC_VER + 0);
-        cf_print("_MSC_FULL_VER", "%lld", _MSC_FULL_VER + 0);
 #endif
         UNUSED(cf_count);
         UNUSED(cf_print);
@@ -517,6 +545,8 @@ void show_sysinfo(const char *options_var) {
         con_fprintf(f, "\n");
         if (e && e[0])
             con_fprintf(f, "Contents of environment variable %s: '%s'\n\n", options_var, e);
+        else if (e)
+            con_fprintf(f, "Environment variable '%s' is set but empty.\n\n", options_var);
         else
             con_fprintf(f, "Environment variable '%s' is not set.\n\n", options_var);
     }
diff --git a/src/options.cpp b/src/options.cpp
index 69bd5599..93c59518 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -39,6 +39,7 @@ std::mutex opt_lock_mutex;
 **************************************************************************/
 
 void Options::reset() noexcept {
+#define opt ERROR_DO_NOT_USE_opt // protect against using the wrong variable
     Options *const o = this;
     mem_clear(o);
     o->crp.reset();
@@ -81,6 +82,7 @@ void Options::reset() noexcept {
     o->win32_pe.compress_rt[24] = false; // 24 == RT_MANIFEST
     o->win32_pe.strip_relocs = -1;
     o->win32_pe.keep_resource = "";
+#undef opt
 }
 
 /*************************************************************************
@@ -88,7 +90,7 @@ void Options::reset() noexcept {
 **************************************************************************/
 
 TEST_CASE("Options::reset") {
-#define opt DO_NOT_USE_opt
+#define opt ERROR_DO_NOT_USE_opt // protect against using the wrong variable
     COMPILE_TIME_ASSERT(std::is_standard_layout<Options>::value)
     COMPILE_TIME_ASSERT(std::is_nothrow_default_constructible<Options>::value)
     COMPILE_TIME_ASSERT(std::is_trivially_copyable<Options>::value)
@@ -97,7 +99,6 @@ TEST_CASE("Options::reset") {
     Options *const o = &local_options;
     o->reset();
     CHECK(o->o_unix.osabi0 == 3);
-    //
     static_assert(TABLESIZE(o->win32_pe.compress_rt) == 25); // 25 == RT_LAST
     CHECK(o->win32_pe.compress_exports);
     CHECK(o->win32_pe.compress_icons);
diff --git a/src/p_lx_elf.cpp b/src/p_lx_elf.cpp
index 650412dc..c6be909f 100644
--- a/src/p_lx_elf.cpp
+++ b/src/p_lx_elf.cpp
@@ -1637,15 +1637,15 @@ PackLinuxElf64amd::defineSymbols(Filter const *ft)
     PackLinuxElf64::defineSymbols(ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf-so_entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf-so_fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.shlib-init.h"
 
 void
@@ -1677,9 +1677,9 @@ PackLinuxElf32x86::buildLoader(const Filter *ft)
         tmp,                       sizeof(stub_i386_linux_elf_fold),  ft );
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-bsd.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-bsd.elf-fold.h"
 
 void
@@ -1705,10 +1705,10 @@ PackBSDElf32x86::buildLoader(const Filter *ft)
         tmp,                     sizeof(stub_i386_bsd_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-netbsd.elf-entry.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-netbsd.elf-fold.h"
 
 #define WANT_NHDR_ENUM
@@ -1738,7 +1738,7 @@ PackNetBSDElf32x86::buildLoader(const Filter *ft)
         tmp,                        sizeof(stub_i386_netbsd_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-openbsd.elf-fold.h"
 
 void
@@ -1764,33 +1764,33 @@ PackOpenBSDElf32x86::buildLoader(const Filter *ft)
         tmp,                     sizeof(stub_i386_openbsd_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-linux.elf-so_entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-linux.elf-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-linux.elf-so_fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5t-linux.shlib-init.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v4a-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v4a-linux.elf-so_entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v4a-linux.elf-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v4a-linux.elf-so_fold.h"
 #if 0
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v4a-linux.shlib-init.h"
 #endif
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/armeb.v4a-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/armeb.v4a-linux.elf-fold.h"
 
 void
@@ -1822,11 +1822,11 @@ PackLinuxElf32armLe::buildLoader(Filter const *ft)
     }
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/mipsel.r3000-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/mipsel.r3000-linux.elf-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/mipsel.r3000-linux.shlib-init.h"
 
 void
@@ -1843,11 +1843,11 @@ PackLinuxElf32mipsel::buildLoader(Filter const *ft)
         stub_mipsel_r3000_linux_elf_fold,  sizeof(stub_mipsel_r3000_linux_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/mips.r3000-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/mips.r3000-linux.elf-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/mips.r3000-linux.shlib-init.h"
 
 void
@@ -1864,9 +1864,9 @@ PackLinuxElf32mipseb::buildLoader(Filter const *ft)
         stub_mips_r3000_linux_elf_fold,  sizeof(stub_mips_r3000_linux_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc-linux.elf-fold.h"
 
 void
@@ -1877,9 +1877,9 @@ PackLinuxElf32ppc::buildLoader(const Filter *ft)
         stub_powerpc_linux_elf_fold,  sizeof(stub_powerpc_linux_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64le-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64le-linux.elf-fold.h"
 
 void
@@ -1890,9 +1890,9 @@ PackLinuxElf64ppcle::buildLoader(const Filter *ft)
         stub_powerpc64le_linux_elf_fold,  sizeof(stub_powerpc64le_linux_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64-linux.elf-fold.h"
 
 void
@@ -1903,15 +1903,15 @@ PackLinuxElf64ppc::buildLoader(const Filter *ft)
         stub_powerpc64_linux_elf_fold,  sizeof(stub_powerpc64_linux_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-linux.elf-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-linux.elf-so_entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-linux.elf-so_fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-linux.shlib-init.h"
 
 void
@@ -1928,15 +1928,15 @@ PackLinuxElf64amd::buildLoader(const Filter *ft)
         stub_amd64_linux_elf_fold,  sizeof(stub_amd64_linux_elf_fold), ft);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm64-linux.elf-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm64-linux.elf-so_entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm64-linux.elf-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm64-linux.elf-so_fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm64-linux.shlib-init.h"
 
 void
diff --git a/src/p_lx_exc.cpp b/src/p_lx_exc.cpp
index 24f83c19..d80ad18c 100644
--- a/src/p_lx_exc.cpp
+++ b/src/p_lx_exc.cpp
@@ -74,14 +74,14 @@ PackBSDI386::PackBSDI386(InputFile *f) : super(f)
     }
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf.execve-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf.execve-fold.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-bsd.elf.execve-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-bsd.elf.execve-fold.h"
 
 
diff --git a/src/p_lx_interp.cpp b/src/p_lx_interp.cpp
index bd03d262..469d2513 100644
--- a/src/p_lx_interp.cpp
+++ b/src/p_lx_interp.cpp
@@ -50,9 +50,9 @@
 //
 **************************************************************************/
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf.interp-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf.interp-fold.h"
 
 PackLinuxElf32x86interp::PackLinuxElf32x86interp(InputFile *f) :
diff --git a/src/p_lx_sh.cpp b/src/p_lx_sh.cpp
index 82a1850d..f7c25486 100644
--- a/src/p_lx_sh.cpp
+++ b/src/p_lx_sh.cpp
@@ -47,9 +47,9 @@
 //
 **************************************************************************/
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf.shell-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.elf.shell-fold.h"
 
 
diff --git a/src/p_mach.cpp b/src/p_mach.cpp
index 96455422..7878916c 100644
--- a/src/p_mach.cpp
+++ b/src/p_mach.cpp
@@ -45,48 +45,48 @@
 #  pragma GCC diagnostic ignored "-Wcast-align"
 #endif
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-darwin.macho-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-darwin.macho-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-darwin.macho-upxmain.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-darwin.dylib-entry.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-darwin.macho-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-darwin.macho-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-darwin.macho-upxmain.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-darwin.dylib-entry.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-darwin.macho-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-darwin.macho-fold.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm64-darwin.macho-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm64-darwin.macho-fold.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc-darwin.macho-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc-darwin.macho-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc-darwin.macho-upxmain.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc-darwin.dylib-entry.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64-darwin.macho-entry.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64-darwin.macho-fold.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64-darwin.dylib-entry.h"
 
 // Packing a Darwin (Mach-o) Mac OS X dylib (dynamic shared library)
diff --git a/src/p_vmlinx.cpp b/src/p_vmlinx.cpp
index adcedc72..63736e2e 100644
--- a/src/p_vmlinx.cpp
+++ b/src/p_vmlinx.cpp
@@ -38,15 +38,15 @@
 #include "p_vmlinx.h"
 #include "linker.h"
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.kernel.vmlinux.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-linux.kernel.vmlinux.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-linux.kernel.vmlinux.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/armeb.v5a-linux.kernel.vmlinux.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc-linux.kernel.vmlinux.h"
 
 
@@ -943,7 +943,7 @@ void PackVmlinuxPPC32::buildLoader(const Filter *ft)
     addLoader("IDENTSTR,UPX1HEAD", nullptr);
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64le-linux.kernel.vmlinux.h"
 void PackVmlinuxPPC64LE::buildLoader(const Filter *ft)
 {
@@ -971,15 +971,15 @@ void PackVmlinuxPPC64LE::buildLoader(const Filter *ft)
 }
 
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.kernel.vmlinux-head.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/amd64-linux.kernel.vmlinux-head.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-linux.kernel.vmlinux-head.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/armeb.v5a-linux.kernel.vmlinux-head.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc-linux.kernel.vmlinux-head.h"
 
 unsigned PackVmlinuxI386::write_vmlinux_head(
@@ -1166,7 +1166,7 @@ bool PackVmlinuxPPC32::has_valid_vmlinux_head()
     return false;
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/powerpc64le-linux.kernel.vmlinux-head.h"
 bool PackVmlinuxPPC64LE::has_valid_vmlinux_head()
 {
diff --git a/src/p_vmlinz.cpp b/src/p_vmlinz.cpp
index 8e0cbb40..d9abdb51 100644
--- a/src/p_vmlinz.cpp
+++ b/src/p_vmlinz.cpp
@@ -37,7 +37,7 @@
 #include "linker.h"
 #include <zlib/zlib.h>
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/i386-linux.kernel.vmlinuz.h"
 
 static const unsigned stack_offset_during_uncompression = 0x9000;
@@ -921,9 +921,9 @@ Linker* PackVmlinuzARMEL::newLinker() const
     return new ElfLinkerArmLE;
 }
 
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-linux.kernel.vmlinux.h"
-static const
+static const CLANG_FORMAT_DUMMY_STATEMENT
 #include "stub/arm.v5a-linux.kernel.vmlinuz-head.h"
 
 void PackVmlinuzARMEL::buildLoader(const Filter *ft)
diff --git a/src/work.cpp b/src/work.cpp
index 3b839172..bd8c7e38 100644
--- a/src/work.cpp
+++ b/src/work.cpp
@@ -30,15 +30,13 @@
 // of class PackerBase which then does the actual work.
 // And see p_com.cpp for a simple executable format.
 
+#define WANT_WINDOWS_LEAN_H 1 // _get_osfhandle, GetFileTime, SetFileTime
 #include "headers.h"
 #if USE_UTIMENSAT
 #include <sys/types.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #endif
-#if defined(_WIN32) || defined(__CYGWIN__)
-#include "util/windows_lean.h" // _get_osfhandle, GetFileTime, SetFileTime
-#endif
 #include "conf.h"
 #include "file.h"
 #include "packmast.h"